Ensure VkPhysicalDevice unwrapping in Device functions

Ensure VkPhysicalDevice unwrapping in Device functions

Certain functions, like vkSetDebugUtilsObjectNameEXT can take a physical device
as a parameter. When this function is queried through vkGetInstanceProcAddr,
the trampoline is returned, whereas when queried through vkGetDeviceProcAddr,
the trampoline wasn't returned, allowing the physical device parameter to not
get unwrapped before calling down the chain, causing a crash.

This commit modifies the codegen to always use the trampoline for these
functions, and adds tests for them. These changes require the the loader check
that the appropriate extensions are enabled during the application's call to
vkGetDeviceProcAddr, since it otherwise always return a non-null function
pointer.